Solubility Determination and Thermodynamic Correlation of 3-Amino-2-methylbenzoic Acid in 12 Monosolvents from 288.15 to 328.15 K

Abstract

A gravimetric method is adopted to measure the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in different solvents, including methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, isobutyl alcohol, 2-butanol, methyl acetate, ethyl acetate, propyl acetate, water, and acetonitrile. Moreover, the experiment is carried out at atmospheric pressure, and the temperature range is from 288.15 to 328.15 K. The solid–liquid equilibrium of 3-amino-2-methylbenzoic acid in all used solvents increases with increasing temperature. In alcohol solvents, except for isopropyl alcohol and 2-butanol, the solubility of 3-amino-2-methylbenzoic acid is positively related to the polarity of the solvent, which follows the “like dissolves like” rule. Because isopropyl alcohol and 2-butanol possess a high hydrogen bond acceptor propensity, this leads to a different solubility behavior. In nonalcohol solvents, the solid–liquid equilibrium of 3-amino-2-methylbenzoic acid also follows the “like dissolves like” rule. Among all 12 solvents, the solid–liquid equilibria of 3-amino-2-methylbenzoic acid in water and acetonitrile are lower than those in alcohols and esters. In addition, the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid were related by the modified Apelblat equation, van’t Hoff equation, and λh equation. Furthermore, all relevant results show consistency with the solid–liquid equilibrium data of 3-amino-2-methylbenzoic acid.